Vehicle brake control apparatus

Abstract

It is checked based on entered information as to whether a vehicle should be decelerated or not (S106). When the vehicle should decelerate, an automatic brake operation is carried out with a braking force being set to be smaller by a predetermined ratio than an estimated maximum braking force estimated based on a road surface friction coefficient μ(S110).

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to a vehicle brake control apparatus having the capability of automatically decelerating or stopping a vehicle to avoid vehicle collision or reducing vehicle damage.[0002]The Japanese Patent Application Laid-open No. 11-348799(1999), corresponding to the U.S. Pat. No. 6,157,892, has already proposed an automatic vehicle brake control technique for the purpose of avoidance of vehicle collision.[0003]However, the above-described conventional vehicle automatic brake control technique is subjected to the following problems. For example, in a condition that the automatic brake operation is started in response to detection of collision danger and almost all of the grip force of a tire friction circle contributes to a braking force, if a driver tries to avoid the vehicle collision with a steering operation, the tire frictional force will deviate from the friction circle and accordingly the driver will not be able to obtain a desired s...

AI Technical Summary

Benefits of technology

[0006]According to the vehicle brake control apparatus of this invention, it becomes possible to realize a stable vehicle brake operation during an automatic brake operation or during a warning brake operation, which is performed to avoid collision danger, regardless of the condition or change of road surface. Furthermore, the vehicle brake control apparatus of this invention can promptly and surely control the behavior of the vehicle in a manner predicted or expected by a driver even in a case that the driver turns or rotates a steering wheel or depresses an accelerator pedal during the automatic brake operation being carried out.

[0020]In the preferred embodiment of the present invention, the braking force restricting element allows the automatic brake operation in which the braking force is maximized when it is judged that the possibility of avoiding vehicle collision by steering is lower than a predetermined rate. With this arrangement, it becomes possible to minimize the collision damage in such serious situation that the steering operation brings no effect in avoiding the vehicle collision.

Problems solved by technology

However, the above-described conventional vehicle automatic brake control technique is subjected to the following problems.

For example, in a condition that the automatic brake operation is started in response to detection of collision danger and almost all of the grip force of a tire friction circle contributes to a braking force, if a driver tries to avoid the vehicle collision with a steering operation, the tire frictional force will deviate from the friction circle and accordingly the driver will not be able to obtain a desired steering force.

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